Green plastics: friend or foe?

‘Is it possible for biodegradable packaging to really do a great disappearing act or is this just a load of landfill?’

This was the big question that was thrashed out recently during the annual breakfast seminar by the Institute of Packaging’s Western Cape region.

It seems that many people who are concerned about the environmental impacts of plastics on the earth, and especially plastics pollution in the environment, had hoped that biodegradable packaging was the big green answer to this problem. I find it almost unavoidable during my organic shopping trips or deliveries. The word ‘bio’ simply immediately feels like the right thing to support, doesn’t it?

But is it really the safest packaging in our country? Do we have the systems in place to deal with this new material and dispose of it in a responsible way? What happens to my biodegradable packaging once I’ve finished using it? Am I able to compost it under perfect conditions in my garden? Or do I know how it’s handled when it leaves my property via the waste truck?

Scientists are concerned

Overseas and local polymer scientists, like Annabe Pretorius and David Hughes from the Plastics Federation of SA are concerned about some serious end-of-life issues connected to the bio, degradable, biodegradable or compostable packaging being used in our country, as they are all forms of plastic.

 

Here are some excerpts from David’s talk:

‘We all want to do our bit for the environment, but is it as simple as purchasing a pack that promises to completely degrade or should we be focusing on recyclable materials? It is all about Carbon management.

Due to concerns about fossil resources depletion, efforts are being made to replace conventional oil, coal and gas-based plastics with others - based on hydrocarbons derived from renewable resources.

There are perceived environmental advantages to using bio-degradable and/or renewable resource plastics (bio-plastics). Besides crude oil, natural gas and coal, plastics can be derived from natural and renewable sources such as wood (cellulose). The problem is that people are claiming that all you do is put an additive into the plastics and the material will magically disappear.

 

Biodegradable is a misused and abused term. What we need is an end-of-life strategy.

The public relations’ strength of the word ‘biodegradability’ carries a lot of weight, but too much flagrant green washing is occurring, with companies announcing eco-claims for products that cannot be backed up with facts.’

Know your carbons

‘Why is replacing petro-carbon with bio-carbon better? Carbon is carbon. There is organic carbon and inorganic carbon. The key component is the carbon building block.

A Plastic may be made from oil, coal, gas (petro), or it may be made from bio material such as sugar cane, converted to ethylene and then into plastics polymers. It may also be made from bio material such as corn, starch, etc and is a hydro material.

It may be degradable, but not biodegradable. It may be biodegradable, but not compostable. It may be biomass, but not biodegradable.

Carbon is the major basic element that is the building block of polymeric materials, bio-based products, petroleum based products, biotechnology products, fuels, even life itself.’

So the issue centres around how to best manage carbon in the most sustainable and environmentally responsible manner. And this seems to be where the problems with bioplastics arrive: Managing Plastics at End-of-Life.’

What happens to bio plastics in the end?

‘Vegetable oils, sugar and starch and can be defined as ‘bio-based’ or ‘bio-mass’ plastics & can be natural or synthetic.

Biobased and biodegradable plastics are single use, short-life, disposable, controlled-life time products like certain packaging, disposable plastics, agricultural films, marine disposable or medical products that can be engineered to be biodegradable/compostable, particularly if the disposal infrastructure is composting, anaerobic digestion, waste water treatment, soil, and similar biological infrastructures.

Bio-based and durable products like soy polyurethanes for cars, or bio-fibre thermoplastic (like polypropylene) composites for industrial and car applications, don’t have biodegradability as a required element. Alternate methods of disposal need to be designed.

Here the polymer is 100% bio-content as the feedstock is ethanol from sugarcane, which is converted to ethylene and follows regular polymerization routes to different polyethylenes.

Preferably recycle or waste to energy

This product is not biodegradable and not recommended for being made degradable with additives approach, because of the serious environmental and health consequences of the degraded fragments in the ecosystem.

The preferred end-of-life scenario is recycling or waste to energy recovery plants.

A plastic is made degradable when it undergoes significant change in the initial properties due to chemical cleavage of the molecular structure. Examples of degradable plastics include oxo-degradables and UV-degradables, which break down when exposed to oxygen or light and are primarily oil-based.

In the case of biodegradability there is a degradation of a polymeric item due, at least in part, to cell-mediated phenomena. As a result of the action of micro-organisms the material is ultimately converted to water, carbon dioxide, biomass and possibly methane.

The ability of a polymer to biodegrade is independent of the origin of its raw material. Instead it strongly depends upon the structure of the polymer. For example, whilst some bio-based plastics may be biodegradable ( e.g. polyhydroxyalkanoates) others are not (e.g. polyethylene derived from sugar cane). Degradation can take weeks or several months.

For a plastic to be considered compostable it must meet the following criteria:

• Biodegrade - break down into carbon dioxide, water and biomass. 90% of the organic materials is converted into CO2 within 6 months.
• Disintegrate: After 3 months’ composting and subsequent sifting through a 2 mm sieve, no more than 10% residue may remain
• Eco-toxicity: the biodegradation does not produce any toxic material and the compost can support plant growth

Why the confusion around bio?

• ‘Bioplastics’ is used to describe two different concepts at the same time, often leading to confusion. Bioplastics does not apply to usual polymers. If it’s described as degradable, it only fragments and doesn’t totally disappear, e.g. UV affected film.
• If it’s described as Bio, it means of organic origin, but not biodegradable!
• Bio-mass means made from agricultural products that consume water, need pesticides, herbicides and fertilizers.
• Bio-mass packaging cannot be recycled along with petro-plastics.
• Biodegradable means that a physical change takes place via an anaerobic processes. It means ‘putrescible.’ (something that is liable to decay)
• Bio-based plastics are not always biodegradable and biodegradable plastics are not always bio-based.

It degrades by biological processes in a commercial / industrial composting facility under strict composting conditions and must disintegrate rapidly and must be designed to degrade and form compost.

The action is a biological process. This is not the same as home composting (where there is insufficient heat to decompose biomass products, it’s below 60 deg C.)

Industrial composting is used for a biodegradable process where material breaks down in a defined environment, under controlled conditions, with no toxic impacts. And it yields methane ‘which can be harnessed for heat or chemicals generation - and CO2 , but no toxins.’

How does biodegradation work?

It involves micro-organisms (bacteria, fungi) that consume plastics fragments, treating them as a food source. It can be either oxo-biodegradable or hydro-biodegradable.

It does NOT mean that ‘it won’t harm the environment.’ It does NOT mean it will readily decompose in a land fill. It means that it requires very specific conditions for it to behave as desired.

If there are insufficient micro-organisms to complete the cycle, the plastic pieces remain an environmental problem. Waste in an advanced stage of biodegradation cannot be recycled with petro plastics, but can be incinerated for energy recovery.

If bio-based products are made from sugar cane derived ethylene, then it behaves as a petro plastic. Or it can be made from starch, etc and then it is a hydro-biodegradable material, which is very different to a petro plastic.

The final product may be mixed with up to 50% of synthetic plastics from oil - and therefore will not behave like a typical biomass product based solely on starch, etc derived from renewable resources.

Green washing clouds the issue

The Plastics Federation of SA (PFSA) is against oxo additives, but understands that it is a fight difficult to win, due to ‘green washing.’

The PFSA is not pro bio plastics, unless they are ethylene routed and durable and complement petro plastics recycling.

The PFSA is not pro bio plastics that are made from starch and are hydro plastics, for very good reasons:

• In South Africa there are no separate waste management streams for petro- oxo-biodegradable/ biomass plastics.
• Neither are there industrial composting facilities in the RSA.
• Biomass [hydro/starch] plastics can be confused with petro plastics, which is catastrophic.
• Oxo-biodegradable plastics (OBDP) will damage the existing SA recycling industry reputation if non-performing products based on OBDP recyclate get sold.
• PFSA don’t believe that OBDP is any sort of end-of-life solution in our country, and it doesn’t solve landfill problems.
• OBDP generates a mass of tiny plastic pieces, which take a long time to get digested and will worsen river and marine toxicity issues.
• We have made an extensive study of the science involved.
• Science isn’t conclusive enough regarding end of oxo-process in all conditions.
• Bioplastics will ruin petro-plastic recyclate if mixed.
• The RSA recycling industry provides employment to thousands in collection and recycling.
• Recycling enjoys strong support from Government that looks to the recycling industry to create more decent jobs through formal programmes.
• RSA does not yet incinerate or recover energy or chemically convert waste.
• Bio plastics are often used by brand owners as ‘green washing’ and without understanding the consequences.

What I came away with from that morning’s seminar is the awareness that bits of bioplastics that land up in the plastic recycling stream pose serious dangers to the recycling industry in our country. It is not always possible for staff at materials recovery centres to identify all the various bioplastics around (mostly imported) and there are no professional industrial composting facilities to send these materials to.

I usually pride myself with sending all our household recyclables to a recycling facility in probably the most jacked up system in the country. But I was shocked to find out today that the bioplastics that I diligently send along with my recyclables to be properly composted are in fact removed, at best, and landfilled. So they end up in the landfill, where their conditions are not suitable for them to biodegrade. If they land up with the recyclable plastics they will contaminate the recycling feedstock, which it degrades with dire consequences - both to the resultant product integrity and to the environment. And the process is not reversible.

There is international concern around the hordes of small plastic particles that arise from degrading polymers (petro or bio) and enter river and marine environments and increase toxic pollution due to the adherence of toxins from other sources.

The rate of biodegradation of these particles is not well researched or documented. In the meantime animals are trapped and killed by products that should have been recycled. Remember plastic doesn’t pollute, people do. This goes to show again that learning to live in the most harmless way possible is a lifelong process.